Chlorophyllα content in the surface and subsurface waters along the course of the SHIRASE to Antarctica in 1984-1985

Abstract

Chlorophyll a concentrations in the surface (by bucket sampling) and subsurface sea waters (by pumping from bottom of ship at ca. 8m depth) were measured along the course of the icebreaker SHIRASE from November 1984 to April 1985,as part of the routine works of marine biology of the 26th Japanese Antarctic Research Expedition (JARE-26). Mean value of the surface chlorophyll a was 0.01mg/m^3 higher than that of the subsurface chlorophyll a. However, the fluctuations of chlorophyll a at both strata showed a similar tendency throughout the cruise. Positive correlation was clearly observed between the surface and the subsurface chlorophyll a. High chlorophyll a concentrations (more than 0.5mg/m^3) were observed in the sea adjacent to Japan, the strait of Malacca and the Southern Ocean. In the Southern Ocean, the chlorophyll a content fluctuated from 0.04mg/m^3 to 1.51mg/m^3. The maximum concentration on the southward leg in early December was 1.51mg/m^3 between the Australasian Subantarctic Front and the Antarctic Convergence. On the other hand, the maximum value on the northward leg in early March was 1.17mg/m^3 near Lat. 62°S.